What tests do you usually write and in what cases are they used?

In Golang, several types of tests are usually written:

• Unit tests — check individual functions or methods for correctness with different input data. Used for quick logic verification without external dependencies.
• Integration tests — verify the interaction of multiple components or working with external services (e.g., databases). Help ensure that parts of the system work together correctly.
• End-to-end tests — test the entire application, simulating real usage scenarios.

In Go, the testing package is used for unit tests. An example of a simple unit test:

func TestSum(t *testing.T) {
    result := sum(2, 3)
    if result != 5 {
        t.Errorf("Expected 5, got %d", result)
    }
}

The choice of test type depends on the task: unit tests — for logic verification, integration — for interaction verification, end-to-end — for user scenario testing.